No useless null in return value of ExpectedInfos.calculate

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/ExpectedInfos.kt

@@ -149,7 +149,7 @@ class ExpectedInfos(
         val useHeuristicSignatures: Boolean = true,
         val useOuterCallsExpectedTypeCount: Int = 0
 ) {
-    public fun calculate(expressionWithType: JetExpression): Collection<ExpectedInfo>? {
+    public fun calculate(expressionWithType: JetExpression): Collection<ExpectedInfo> {
         val expectedInfos = calculateForArgument(expressionWithType)
                             ?: calculateForFunctionLiteralArgument(expressionWithType)
                             ?: calculateForEqAndAssignment(expressionWithType)
@@ -164,7 +164,7 @@ class ExpectedInfos(
                             ?: calculateForLoopRange(expressionWithType)
                             ?: calculateForInOperatorArgument(expressionWithType)
                             ?: getFromBindingContext(expressionWithType)
-                            ?: return null
+                            ?: return emptyList()
         return expectedInfos.filterNot { it.fuzzyType?.type?.isError ?: false }
     }
 
@@ -188,8 +188,8 @@ class ExpectedInfos(
         return calculateForArgument(call, argument)
     }
 
-    public fun calculateForArgument(call: Call, argument: ValueArgument): Collection<ExpectedInfo>? {
-        val results = calculateForArgument(call, TypeUtils.NO_EXPECTED_TYPE, argument) ?: return null
+    public fun calculateForArgument(call: Call, argument: ValueArgument): Collection<ExpectedInfo> {
+        val results = calculateForArgument(call, TypeUtils.NO_EXPECTED_TYPE, argument)
 
         fun makesSenseToUseOuterCallExpectedType(info: ExpectedInfo): Boolean {
             val data = info.additionalData as ArgumentAdditionalData
@@ -202,21 +202,21 @@ class ExpectedInfos(
             val callExpression = (call.callElement as? JetExpression)?.getQualifiedExpressionForSelectorOrThis() ?: return results
             val expectedFuzzyTypes = ExpectedInfos(bindingContext, resolutionFacade, moduleDescriptor, useHeuristicSignatures, useOuterCallsExpectedTypeCount - 1)
                     .calculate(callExpression)
-                    ?.map { it.fuzzyType }
-                    ?.filterNotNull() ?: return results
+                    .map { it.fuzzyType }
+                    .filterNotNull()
             if (expectedFuzzyTypes.isEmpty() || expectedFuzzyTypes.any { it.freeParameters.isNotEmpty() }) return results
 
             return expectedFuzzyTypes
                     .map { it.type }
                     .toSet()
-                    .flatMap { calculateForArgument(call, it, argument) ?: emptyList() }
+                    .flatMap { calculateForArgument(call, it, argument) }
                     .toSet()
         }
 
         return results
     }
 
-    private fun calculateForArgument(call: Call, callExpectedType: JetType, argument: ValueArgument): Collection<ExpectedInfo>? {
+    private fun calculateForArgument(call: Call, callExpectedType: JetType, argument: ValueArgument): Collection<ExpectedInfo> {
         val argumentIndex = call.getValueArguments().indexOf(argument)
         assert(argumentIndex >= 0) {
             "Could not find argument '$argument' among arguments of call: $call"
@@ -236,7 +236,7 @@ class ExpectedInfos(
             override fun getFunctionLiteralArguments() = emptyList<FunctionLiteralArgument>()
             override fun getValueArgumentList() = null
         }
-        val resolutionScope = bindingContext[BindingContext.RESOLUTION_SCOPE, call.calleeExpression] ?: return null //TODO: discuss it
+        val resolutionScope = bindingContext[BindingContext.RESOLUTION_SCOPE, call.calleeExpression] ?: return emptyList() //TODO: discuss it
 
         val dataFlowInfo = bindingContext.getDataFlowInfo(call.calleeExpression)
         val bindingTrace = DelegatingBindingTrace(bindingContext, "Temporary trace for completion")
@@ -371,13 +371,13 @@ class ExpectedInfos(
         return when (expressionWithType) {
             ifExpression.getCondition() -> listOf(ExpectedInfo(KotlinBuiltIns.getInstance().getBooleanType(), null, Tail.RPARENTH))
 
-            ifExpression.getThen() -> calculate(ifExpression)?.map { ExpectedInfo(it.filter, it.expectedName, Tail.ELSE) }
+            ifExpression.getThen() -> calculate(ifExpression).map { ExpectedInfo(it.filter, it.expectedName, Tail.ELSE) }
 
             ifExpression.getElse() -> {
                 val ifExpectedInfo = calculate(ifExpression)
                 val thenType = ifExpression.getThen()?.let { bindingContext.getType(it) }
                 if (thenType != null && !thenType.isError())
-                    ifExpectedInfo?.filter { it.matchingSubstitutor(thenType) != null }
+                    ifExpectedInfo.filter { it.matchingSubstitutor(thenType) != null }
                 else
                     ifExpectedInfo
             }
@@ -395,7 +395,7 @@ class ExpectedInfos(
                 val leftType = bindingContext.getType(leftExpression)
                 val leftTypeNotNullable = leftType?.makeNotNullable()
                 val expectedInfos = calculate(binaryExpression)
-                if (expectedInfos != null) {
+                if (expectedInfos.isNotEmpty()) {
                     return if (leftTypeNotNullable != null)
                         expectedInfos.filter { it.matchingSubstitutor(leftTypeNotNullable) != null }
                     else
@@ -417,16 +417,16 @@ class ExpectedInfos(
         if (functionLiteral != null) {
             val literalExpression = functionLiteral.parent as JetFunctionLiteralExpression
             return calculate(literalExpression)
-                    ?.map { it.fuzzyType }
-                    ?.filterNotNull()
-                    ?.filter { KotlinBuiltIns.isExactFunctionOrExtensionFunctionType(it.type) }
-                    ?.map {
+                    .map { it.fuzzyType }
+                    .filterNotNull()
+                    .filter { KotlinBuiltIns.isExactFunctionOrExtensionFunctionType(it.type) }
+                    .map {
                         val returnType = KotlinBuiltIns.getReturnTypeFromFunctionType(it.type)
                         ExpectedInfo(FuzzyType(returnType, it.freeParameters), null, Tail.RBRACE)
                     }
         }
         else {
-            return calculate(block)?.map { ExpectedInfo(it.filter, it.expectedName, null) }
+            return calculate(block).map { ExpectedInfo(it.filter, it.expectedName, null) }
         }
     }
 

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/Weighers.kt

@@ -217,7 +217,7 @@ class SmartCompletionInBasicWeigher(private val smartCompletion: SmartCompletion
 
         if ((o as? DeclarationLookupObject)?.descriptor in descriptorsToSkip) return DESCRIPTOR_TO_SKIP_WEIGHT
 
-        if (expectedInfos == null || expectedInfos.isEmpty()) return NO_MATCH_WEIGHT
+        if (expectedInfos.isEmpty()) return NO_MATCH_WEIGHT
 
         val smartCastCalculator = smartCompletion.smartCastCalculator
 

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/handlers/GenerateLambda.kt

@@ -79,7 +79,7 @@ private fun needExplicitParameterTypes(context: InsertionContext, placeholderRan
     val resolutionFacade = file.getResolutionFacade()
     val bindingContext = resolutionFacade.analyze(expression, BodyResolveMode.PARTIAL)
     val expectedInfos = ExpectedInfos(bindingContext, resolutionFacade, resolutionFacade.findModuleDescriptor(file), useHeuristicSignatures = false)
-                                .calculate(expression) ?: return false
+                                .calculate(expression)
     val functionTypes = expectedInfos
             .map { it.fuzzyType?.type }
             .filterNotNull()

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/smart/SmartCompletion.kt

@@ -63,7 +63,7 @@ class SmartCompletion(
     private val receiver = if (expression is JetSimpleNameExpression) expression.getReceiverExpression() else null
     private val expressionWithType = receiver?.parent as? JetExpression ?: expression
 
-    public val expectedInfos: Collection<ExpectedInfo>? = calcExpectedInfos(expressionWithType)
+    public val expectedInfos: Collection<ExpectedInfo> = calcExpectedInfos(expressionWithType)
 
     public val smartCastCalculator: SmartCastCalculator = SmartCastCalculator(bindingContext, moduleDescriptor, expression)
 
@@ -113,7 +113,7 @@ class SmartCompletion(
     private fun executeInternal(): Result? {
         val (additionalItems, inheritanceSearcher) = additionalItems()
 
-        if (expectedInfos == null || expectedInfos.isEmpty()) {
+        if (expectedInfos.isEmpty()) {
             return Result(null, additionalItems, inheritanceSearcher)
         }
 
@@ -147,14 +147,14 @@ class SmartCompletion(
     public fun additionalItems(): Pair<Collection<LookupElement>, InheritanceItemsSearcher?> {
         val asTypePositionItems = buildForAsTypePosition()
         if (asTypePositionItems != null) {
-            assert(expectedInfos == null)
+            assert(expectedInfos.isEmpty())
             return Pair(asTypePositionItems, null)
         }
 
         val items = ArrayList<LookupElement>()
         val inheritanceSearchers = ArrayList<InheritanceItemsSearcher>()
 
-        if (expectedInfos != null && expectedInfos.isNotEmpty() && receiver == null) {
+        if (expectedInfos.isNotEmpty() && receiver == null) {
             TypeInstantiationItems(resolutionFacade, moduleDescriptor, bindingContext, visibilityFilter, toFromOriginalFileMapper, inheritorSearchScope, lookupElementFactory, forBasicCompletion)
                     .addTo(items, inheritanceSearchers, expectedInfos)
 
@@ -198,11 +198,11 @@ class SmartCompletion(
         }
     }
 
-    private fun calcExpectedInfos(expression: JetExpression): Collection<ExpectedInfo>? {
+    private fun calcExpectedInfos(expression: JetExpression): Collection<ExpectedInfo> {
         if (forBasicCompletion) {
             return ExpectedInfos(bindingContext, resolutionFacade, moduleDescriptor, useOuterCallsExpectedTypeCount = 0)
                     .calculate(expression)
-                    ?.map { it.copy(tail = null) }
+                    .map { it.copy(tail = null) }
         }
 
         // if our expression is initializer of implicitly typed variable - take type of variable from original file (+ the same for function)
@@ -222,7 +222,7 @@ class SmartCompletion(
         var count = 0
         while (true) {
             val infos = ExpectedInfos(bindingContext, resolutionFacade, moduleDescriptor, useOuterCallsExpectedTypeCount = count)
-                    .calculate(expression) ?: return null
+                    .calculate(expression)
             if (count == 2 /* use two outer calls maximum */ || infos.none { it.fuzzyType?.isAlmostEverything() ?: false }) return infos
             count++
         }
@@ -342,7 +342,7 @@ class SmartCompletion(
                         ?: return null
         val elementType = binaryExpression.getOperationReference().getReferencedNameElementType()
         if (elementType != JetTokens.AS_KEYWORD && elementType != JetTokens.AS_SAFE) return null
-        val expectedInfos = calcExpectedInfos(binaryExpression) ?: return null
+        val expectedInfos = calcExpectedInfos(binaryExpression)
 
         val expectedInfosGrouped: Map<JetType?, List<ExpectedInfo>> = expectedInfos.groupBy { it.fuzzyType?.type?.makeNotNullable() }
 

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/smart/SmartCompletionSession.kt

@@ -106,9 +106,7 @@ class SmartCompletionSession(configuration: CompletionSessionConfiguration, para
 
                     val expectedInfos = ExpectedInfos(bindingContext, resolutionFacade, moduleDescriptor)
                             .calculateForArgument(dummyCall, dummyArgument)
-                    if (expectedInfos != null) {
-                        collector.addElements(LambdaItems.collect(expectedInfos))
-                    }
+                    collector.addElements(LambdaItems.collect(expectedInfos))
                 }
             }
         }